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Wet Spot

12-01-2009, 09:45 AM

Any help on this is appreciated. No one can seem to solve this problem.

I have a recurring wet spot outside our bathroom area on the outside of our one-story house. It is outside of a shower stall/bath area. Inside the wall there is nothing but a black PVC vent pipe. We have had several plumbers over and they have each told us the same thing: it is from a leak in the caulking that seals the acrylic shower panels. I had the shower panels removed and re-caulked and that did not solve the problem. Each plumber said that if it were water inside the vent pipe (that is higher than the tub) that water would also appear in the tub (since water seeks its own level). That made sense but the wet spot on the concrete outside the home persists even when we do not use that bathroom. It generally appears overnight and dries by the end of the afternoon.

We have gone so far as to completely replace the shower with a fully sealed tile shower. No luck -- the wet spot is still there. I had a roofer over to check the roofing -- he said that it was not that.

My next step is to rip out the exterior siding to get a closer look at the vent pipe...I'd like to avoid that. If anyone has any ideas, all of them are welcomed.

Thanks so much for your help. I'll be glad to address anything that needs clarification.

slightly confused here, is the wet spot on the exterior wall of the house? or on the ground?

and how is it wet, running water, condensation type beads of water, a stream of water?

Is the wet area, the basic size of the wall of the bath room or just one small spot if it is on the wall?

one more question do you have a vent fan in the bath room?

and what type of vapor barrier is in the wall? Is there insulation in the wall?

~~~~~~~~~~~~~~~~~~~~~~~~
Making some guesses here, but if there is little or no vapor barrier and little or no insulation, and if the bath room is left in a high humidity state when done showering, and the temperature is cooler in the night than the interior of the house, my guess it is water vapor condensing on the exterior wall and running out from under the siding.

I have a neighbor who could never keep the exterior wall on the bath room painted, all the rest of the wall was fine, and it appeared that the moisture of the shower would migrate through the wall and through the siding and push the paint off the building,

There answer was to side with vinyl siding. and cover up the problem.

Push sticks/blocks Save Fingers
~~~~~~~~~~~~~~~~~~~
"The true measure of a man is how he treats someone who can do him absolutely no good."
attributed to Samuel Johnson
~~~~~~~~~~~~~~~~~~~
PUBLIC NOTICE: Due to recent budget cuts, the rising cost of electricity, gas, and oil...plus the current state of the economy............the light at the end of the tunnel, has been turned off.

Comment

slightly confused here, is the wet spot on the exterior wall of the house? or on the ground?

and how is it wet, running water, condensation type beads of water, a stream of water?

Is the wet area, the basic size of the wall of the bath room or just one small spot if it is on the wall?

one more question do you have a vent fan in the bath room?

and what type of vapor barrier is in the wall? Is there insulation in the wall?

~~~~~~~~~~~~~~~~~~~~~~~~
Making some guesses here, but if there is little or no vapor barrier and little or no insulation, and if the bath room is left in a high humidity state when done showering, and the temperature is cooler in the night than the interior of the house, my guess it is water vapor condensing on the exterior wall and running out from under the siding.

I have a neighbor who could never keep the exterior wall on the bath room painted, all the rest of the wall was fine, and it appeared that the moisture of the shower would migrate through the wall and through the siding and push the paint off the building,

There answer was to side with vinyl siding. and cover up the problem.

Thanks for your response.

Wet spot is about 12" long and at it's widest point 1.5" wide. It is on the ground (concrete slab) that contacts the exterior wall of the house. It is just a wet spot on the concrete. Yes, there is a vent fan in the bathroom -- we've never used it since it's very dry here in NM and the bathroom is quite large. There is insulation in the wall. The vapor barrier is the barrier that's on the insulation as well as a black fiberboard. Hope this helps.

Comment

Knowing that I'd have to do it anyway, I went ahead and opened up the exterior wall to see what's going on. I immediately found the leak (SEE PICTURE).

In the picture is the piece of 1.5" vent pipe that I removed. Observe the joint at the elbow. It looks as though, when the plumbers were installing the pipe, they got some wood chips/flakes/etc. jammed into the joint while they were cementing the elbow to the pipe. At night, condensation occurred and built up in the vent pipe. It gathered in this particular spot because the plumbers did not install any downward grade to it, thus causing the condensation to build up and then leak out of the elbow which was not completely sealed.

Push sticks/blocks Save Fingers
~~~~~~~~~~~~~~~~~~~
"The true measure of a man is how he treats someone who can do him absolutely no good."
attributed to Samuel Johnson
~~~~~~~~~~~~~~~~~~~
PUBLIC NOTICE: Due to recent budget cuts, the rising cost of electricity, gas, and oil...plus the current state of the economy............the light at the end of the tunnel, has been turned off.

Comment

Knowing that I'd have to do it anyway, I went ahead and opened up the exterior wall to see what's going on. I immediately found the leak (SEE PICTURE).

In the picture is the piece of 1.5" vent pipe that I removed. Observe the joint at the elbow. It looks as though, when the plumbers were installing the pipe, they got some wood chips/flakes/etc. jammed into the joint while they were cementing the elbow to the pipe. At night, condensation occurred and built up in the vent pipe. It gathered in this particular spot because the plumbers did not install any downward grade to it, thus causing the condensation to build up and then leak out of the elbow which was not completely sealed.

Comment

This was the work of a licensed Plumber? Not just a "plumber" but a licensed one?

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